EFFECT OF ANNEALING TEMPERATURE ON MAGNETIC AFTER-EFFECT IN FECUNBSIBALLOYS

The microstructure and magnetic properties i.e. the initial permeabili ty, magnetic after-effect and coercivity for the as-quenched and annea led at different temperatures Fe79.5Cu1Nb3Si13.5B9 samples are studied After annealing the samples at 573 K for 1 h the decrease of the init ial permeability and increase of the disaccommodation amplitude are ob served These are connected with a local anisotropy induced during this treatment. The increase of the annealing temperature causes the impro vement of soft magnetic properties. However, after annealing the toroi dal samples at 723 K for 1 h a magnetic hardening is observed It seems to be connected with the appearance of alpha Fe-Si nuclei and cluster s enriched in Cu. Moreover, it was stated that the cooling conditions of the samples influence also their magnetic properties. Therefore, th e values of coercivity obtained for annealed strips in comparison with corresponding results of mu' obtained for toroids are shifted towards higher temperature by 50 K.